Deborah Hasin, PhD, professor of epidemiology in the Department of Psychiatry at Columbia University Medical Center
NEW YORK — As laws and attitudes about marijuana use have been relaxed over the past two decades, the substance has become widely regarded by society as innocuous. Yet as many as one-third of people who use marijuana develop cannabis-use disorder, characterized by craving cannabis, difficulty controlling cannabis use, problems at work or school due to cannabis use or giving up other activities in favor of cannabis use.
Although a few studies have examined the incidence of cannabis use disorder among the general population in states where medical and/or recreational use of marijuana has been legalized, a new study published in The American Journal of Psychiatry is the first to show the effects of these laws on veterans specifically. 1
Deborah Hasin, PhD, professor of epidemiology in the Department of Psychiatry at Columbia University Medical Center, led the new study because she thought it was important to get more information about the effects of the cannabis laws in veterans, who have “a lot of potential risk for substance-abuse disorders,” she said. “Because of exposure to injury to during service and psychiatric disorders, they are more vulnerable to cannabis-use disorders as a group.”
Hasin and her colleagues used VHA electronic health records from 2005 to 2019 to identify the percentage of VHA patients seen each year with a cannabis-use disorder diagnosis. They examined trends in cannabis-use disorder by age and by race/ethnicity and sex within age groups. Overall, the study found diagnoses of cannabis-use disorder increased in all age groups and demographics over the study period.
Specifically, in 2005, the percentages of VHA patients diagnosed with cannabis-use disorder in the under-35, 35-64, and 65 and older age groups were 1.70%, 1.59% and 0.03%, respectively, the researchers found. By 2019, the percentages had increased to 4.84%, 2.86% and 0.74%, respectively. Although the prevalence of cannabis-use disorder was consistently higher among males than females, between 2016 and 2019, the prevalence increased more among females than males in the under-35 year group. Black patients had a consistently higher prevalence of cannabis-use disorder than other racial/ethnic groups, and increases were greater among Black than white patients in the under-35 year group in both periods.
Not surprisingly, increases were greatest in states that had legalized medicinal or recreational use of marijuana, the researchers found. “We knew what state they lived in, so we were able to look at differences in the rates of cannabis-use disorder before and after the passage of the laws and, importantly, we were able to look at differences in the rates of cannabis-use disorder before and after the passage of the laws, and importantly we were able to compare those to states that during the same time didn’t change their laws,” Hasin said.
Key Findings
“The key findings were that both medical marijuana laws and recreational laws did lead to greater increases in cannabis-use disorder diagnoses in states that changed their laws, compared to other states,” she continued. However, the effect of the laws alone didn’t account for the whole increase over time, Hasin told U.S. Medicine.
The authors speculated that other influences going on during the study period –including the growing commercialization of cannabis—were responsible in part for the increases. Also, attitudes from states where cannabis is legal likely spilled over into other states. “At least two-thirds of the U.S. states at this point have legalized cannabis for medical purposes, and about a quarter of the states now have legalized recreational use. So is a big change, even if you don’t live in a state that made those changes legally,” said Hasin. “Especially for young people, it is not that hard to find cannabis if you want to get it, and I think there is just a big change in attitude going on.”
For clinicians working with veterans, this change means being aware of cannabis-use disorder and the impairment associated with it, Hasin said. “So instead of saying ‘Oh it’s fine, it’s normal now,’ it is probably a good idea for clinicians to screen for cannabis use and, if there is heavy use, there to screen a little bit additionally for signs of cannabis-use disorder and then, with respect to the patient, discuss the implications of that for the patient.”
The researchers are conducting additional studies now, looking at whether the effects of these laws are stronger in clinical subgroups, such as patients with particularly painful medical conditions or patients with particular psychiatric disorders, said Hasin, adding she expect those studies to be published later this year or early next year.
- Hasin DS, Saxon AJ, Malte C, Olfson M, et. al. Trends in Cannabis Use Disorder Diagnoses in the U.S. Veterans Health Administration, 2005-2019. Am J Psychiatry. 2022 Jul 28:appiajp22010034. doi: 10.1176/appi.ajp.22010034. Epub ahead of print. PMID: 35899381.